Radio communication



June 12, 1934. A. NYMAN RADIO COMMUNICATION Filed Sept. 8. 1926 4Sheets-Sheet l nun ll/W/l/ I1 I 1.11 .1 I l 1 I d IN VE N TOR a/exanderNyman a Y 74%;?

HTTORP/EY June 12, 1934.

A. NYMAN 1,962,611 RADIO COMMUNICATION Filed Sept. 8. 1926 4Sheets-Sheet 2 1 Q m B m %q a T \D N INVEHTOR d/emnder Hym n BY a ATORNEY June 12, 1934. A. NYMAN RADIO COMMUNICATION Filed Sept. 8. 1926 4Sheets-Sheet 3 IHVENTOR d/exander I'll man BY r v 7? HTTOEHEY 31 tionare fully pointed out.

Patented June 12, 1934 UNITED STATES PATENT OFFICE 1,962,611 RADIOCOMMUNICATION Alexander Nyman, Dobbs Ferry, N. Y., assignor to DubilicrCondenser Corporation; New York,

N. Y., a corporation of Delaware Application September 8, 1926, SerialNo. 134,294

i l 12. Claims.

I have invented improvements in radio communication; particularly thesending and receiving of radio messages. The invention aims to provide amethod and apparatus by which l messages can be conveniently andinexpensively sent along electric conductors extending over a greater orless distance to carry electrical current from one point to another,such conductors being generally known as electrical transmission lines.I

A further object of the invention is to provide for the sending andreceiving of wired radio messages over electrical transmission lines byapparatus comprising portable devices which can easi- Ely be connectedto the transmission line at a desired point and operated to enable wiredradio messages to be sent to that point and easily received anywherewithin a prescribed radius of the vicinity thereof.

The nature of the invention is set forth in the following description,taken with the drawings which illustrate in preferred form the apparatusby which my invention is practiced, and in the appended claims the novelfeatures of the inven- But I of course reserve the right to make changesin the shape, size and arrangement of the parts or manner of proceedingthat come within the principle of the invention, and are embraced withinthe meanings of the broad terms in which the appended claims areexpressed.

n the drawings: Figure 1 shows how radiomessagesmay be sent along apower line to a given point and there i distributed;

Figure 2 shows diagrammatically the kind of receiving set which isemployed; and

Figures 3 and 4 are modifications of the apparatus shown in Figurel.

The same numerals identify the same parts throughout.

Referring first to Figure 1, I show at l a pole or tower having across-arm 2 at the top to support the electric conductors 3 of a powertransmission 5 line, these conductors being suspended from the cross-arm2 by strings of insulators 4. It is wellknown that electric waves ofhigh frequency will travel along such a line without interfering withthe power which the line transmits. Through the medium of such wavesmessages can be sent and received at any desired point to which the linemay extend. In practice, I arrange for the reception of messagesindividually along the line 3 at any desired number ofpointsythemessages i reaching the points in question and being there distributedthrough the vicinity, so that persons in the neighborhood of such pointsmay receive such messages. One of such points of distribution isindicated in Figure hwhere 5 indicates local transmitting apparatusillustrated-as being disposed in a casing 6, suspended from one of theconductors 3. For this purpose I hang a suspension bar 7 at theend ofone string of insulators 4, and from the ends of this bar hang rods 8which pass into the casing 6. These rods may be fastened rigidly to thecasing and will be in contact with the adjacent conductor 3, as byhaving openings through which this conductor passes. Between the rods 8,the conductor 3 will be coiled up in the form of a winding 9. The casing6 may be of any suitable material, but in the event that it is made ofmetal, the rods 8 will pass into it through insulating bushings 10, andthe inner ends of these rods will be connected by a condenser 11 andcoil 12 in series. Thus electric waves passing along the conductor 3having coil 9 in the line thereof will set up oscillations in the localcircuit comprising this coil with the condenser 11 and coil 12, and suchoscillations can be radiated by the apparatus in the casing 6, so thatthe messages can be picked up by anyone for whom they are intendedwithin a predetermined distance.

I prefer to make the appliances within the easing v6 radiate say fromone thousand to two thousand kilocycles. The electric waves travellingalong the conductors 3 will have a frequency of twenty to thirtykilocycles, and perhaps more, longer waves being more suitable fortransmission along the wires, because they follow the wires and areradiated away from them to a less extent than the shorter waves. Theapparatus in the casing 6 should therefore receive at twenty to thirtykilocycles or over, and radiate at a much shorter wave length. I furtherdispose in the casing 6 a modulator and oscillator so that the frequencyof the oscillations on the conductors 3 can be converted and given ahigher value as required.

The modulator is shown as having the form of a vacuum tube 13 with itsgrid connected to one end of the coil 12, and its filament connected tothe other end of the coil 12 between same and condenser 11. The plate ofthe modulator tube 13 is connected to a choke coil 14 and thence to'theplate or anode of the oscillator which likewise in the form of a vacuumtube and is shown at 15. The two heated cathodes of the tubes 13 and arejoined in parallel by two wires 1'? running to a battery tube 15 isjoined a coil 18 at one point, the one extremity of this coil beingunited to the cathode maining extremity of the coil 18 is led outthrough the casing 6 to make pendant antenna 21. The battery B whichenergizes the anodes of the tubes This method affords a very importantadvantage over the usual device by which a portable set is usuallyconnected to a temporary antenna in close proximity to the transmissionline.

23 is connected to the the remaining terminal the lead Z. The circuitsanode of the second tube primary of a transformer, of which is alsojoined to condenser c, the same as the first tube 26. In the second tube26 the electrical oscillations are detected at twenty to thirtykilocycles and from this second tube they are passed to another trans-The plate of the ceived by the receiver T.

Figure 3 shows another form of instrument for taking oscillations fromthe line Wires and converting them from the lower to the higher throughan opening in the and terminates in an eyelet,

the current constant. in operative relation up so as to The transformer31 is put by moving the switch 34 bridge over the switch contacts 43 ona plunger 44 operated by a coil 45. This solenoid 45, when the switchcontacts 42 are closed, is in series lot ' The oscillations from tubesand 0'.

tube M, and the other terminal'is connected to one terminal of thebattery 13,. and by lead 38 to the center point of resistor 38. Theanode of the tube M is connected through the choke coil 14 and an ironchoke coil 16 to the positive terminal of the battery B. The anode ofthe oscillator tube 0 is connected through a tickler coil 20 to a pointbetween the high frequency coil 14 and the iron coil 16. The grid of themodulator tube M is connected to the coil 12 of the pickup system, whilethe grid of the oscillator O is connected to the primary oi theoscillatingtransformer 18. The opposite terminal of this transformer isconnected to the negative end of the battery. The pendant antenna 21 isconnected through the secondary coil 29 of the oscillation transformerto lead'46 on the negative side of the battery B. The other extremity ofthe coil 12 is also connected to lead 46. A condenser 19 bridges thecoil 18, and an iron core inductance 16 is connected to a point betweenthe coils 14 and 20, and the other terminal of the battery 13. The leadwhich connects the coil 12 to the battery is shown at 4'7.

When the switch arm 34 is moved upward, current'from the transformer 31flows through the lead 39 to the filament of the tube M and the filamentof the tube 0, returning by way of contacts 42, solenoid45, resistance3'7 and the lead 33.

wire 3 are used to modulate the output by means of the tube M. Themodulations are applied to the oscillator tube 0 and'the signals arethus converted to a higher frequency and then radiated from the antenna31 which is inductively coupled to the instrument.

I provide a duplicate modulator tube M and a duplicate modulator tube 0.The tubes M and M have their grids and anodes connected in parallel, andso have the grids and anodes of the The filaments of the tubes 0 and Mare united at one terminal to one terminal of the filaments O and M, andtheir other terminals are united by wires 41 to switch contacts 42 to bebridged by a member 43 at the lower end of the plunger 44. If inoperation the filaments of the tubes M or O burn out, the coil becomespartially de-energized so that the plunger 44 can drop and bridge thecontacts 42, and thus the filaments of the tubes M and O can be heated.On the upward movement, the lever 34, as stated above, actuates the linkL to lift the plunger 44 and bridge the contacts 42. This movement makesthe lower end of the link L slip past the armA, but the plunger 44 isnow held up by the coil 45. If either of tubes M and O burn out and thecoil 45 becomes de-energized, the plunger 44 can drop to bridge thecontacts 42, and thus put the tubes M and 0 into circuit. Between thefilament of the tube M and the lead between the coils l4 and 20 is acondenser 19. The rods 8 have hooks to hang the casing 6 on theconductor 3.

A further form of instrument for taking oscillations from the line 3 isshown in Figure 4, where the casing 6 and contents are hung as before onrods 8 from the wire 3. A lead 4'7, as before, connects one end of thecoil 12 to common terminals of batteries A and B, and the other end isjoined to the grid of the modulator tube 13. This instrument is arrangedto be started by an impulsealong the transmission line to operate amechanical switch and close the filament circuits of the modulator andoscillator. The switch comprises two coils 48 and 48 in parallel,connected through a crystal detector to the terminal of the coil 12which lies between the coil and the condenser 11. The common terminal ofthe coils 48 and 48 are connected to the opposite terminal of thecondenser 11, or between this terminal and the rod 8 leading to the line3. A condenser C bridges the coil 48. From the terminal of the coil 48connected to the detector 49 a lead 50 runs to the terminal of the coil48 opposite to that connected to the coil 48, and this coil is alsobridged by a condenser C. The coil 48 and associate condenser maybetuned to a frequency of say ten cycles, and the coil 48 and itsassociate condenser C tuned to say twelve cycles. The twenty kilocycleoscillations of the wire 3 which have been modulated at, for example,ten cycles are demodulated by the detector 49 to ten cycles to energizethe coil 48. This coil will actuate a plunger 44, carrying a switchmember 43 to bridge two fixed contacts 42. One of these contacts isconnected by a wire 17 to the other terminal of the battery A, and theother contact is connected by wire 17 to the two filaments of themodulator tube 13 and oscillator tube 15. Conductors 17a join the otherterminals of the filaments to the terminal of the battery A, joined tothe battery B. Hence, when a ten cycle current passes through the coil48, the switch member 44 will close the filament circuit, and the tubes13 and 15 will be energized. The terminal of the coil 12, connected tothe condenser 11, is united to the grid of the tube 13, the plate ofwhich is connected through a choke coil 14 to the plate of theoscillator tube 15. The grid of this oscillator tube is connectedthrough a condenser C to one terminal of the coil 18, united to apendant antenna 21. The outside terminal of this coil is united througha condenser C to the plate of the tube 15, and a point between theextremities of the coil is united by a lead 51 to the filament of thetube '15. The terminal of the battery B opposite to that connected tothe coil 12 is joined to the lead between the plates of the tubes 13 and15 through an iron core inductance 16. A twelve cycle signal will takeefiect through the coil 48, which is wound in the opposite directionwith respect to the coil 48, and move the plunger to carry the member 43away from the contact 42. The circuit connected to the antenna is thewellknown Hartley oscillating circuit. With the instrument shown inFigure 4, connection can be made with a transmission line at any desiredpoint, and the apparatus can be moved at will.

The ten cycle calling signal and the twelve cycle disconnecting signalare transmitted as a modulation of the twenty or thirty kilocyclesending wave. Instead of the disconnecting signal, the plunger 44 may bepulled by a spring against the action of coil 48. When the ten cyclesignal ceases, the plunger is pulled out and the filament circuitopened. In this latter case, coil 48 and condenser C may be omitted.

Having described my invention, what I believe to be new and desire tosecure and protect by Letters Patent of the United States is:-

l. A signaling system comprising a transmission line, means forsuperposing a modulated carrier current on said line, and a radiotransmitting set operatively associated with said line to broadcastsignals transmitted by the carrier and normally in inoperativecondition, said set comprising means for receiving said carrier current,means controlled by said carrier current for automatically putting saidtransmitting set into operative condition and causing it to send outradio frequency waves, and means for modulating the radio frequencywaves in accordance with said modulated carrier.

2. A signaling system comprising a transmission line, means forsuperposing a modulated carrier carrier for putting said sets intooperative condition and automatically generating and sending out radiofrequency waves, and means for modulating the radio frequency waves inaccordance with said modulated carrier.

3. A signaling system comprising a transmission line having a modulatedcarrier current superposed therewith, means within said radio setsautomatically actuated by the carrier current to put the sets inoperative condition to broadcast locally, said radio sets comprisingmeans for retransmitting modulations of said carrier at radiofrequencies.

4. A radio signaling system comprising a plurality of radio broadcastingsets situated at intervals, a transmission line associated with saidradio sets and having signal-1nodulated carrier currents impressedthereon, means within each of said radio sets responsive to the carriercurrents to put the sets in operative condition, and means formodulating the outputs of said radio sets in accordance with thesignals.

5. A signaling system comprising a plurality of radio transmitting setssituated at intervals, a transmission line associated with saidtransmitters and mitters operable by the carrier current for putting thesets in communicative relation with said transmission line, and meanswhereby a signal transmitted by the carrier current over said line inoperating condition, and means to modulate the output of said set inaccordance with the modulated carrie current received.

g magnetic waves, said apparatus being responsive to a given carriercurrent superposed upon the transmission line, and means to modulate theoutput of the transmitting set in accordance with the modulated carriercurrent received.

quency, said means being responsive to a modulated carrier current of agiven frequency superposed upon the transmission line, and means formodulating the output of the transmitter in accordance with themodulated carrier current received.

9. In a signaling system, a plurality of radio broadcast transmitters, atransmission line multinly associated with said transmitters, meanscarrier current upon current for putting the same into communicativerelation with the transmission line, and means Within the transmittersfor modulating their outputs in accordance with the modulated carriercurrent, whereby the carrier current signals can be sent out from all ofsaid radio transmitters simultaneously.

10. A signaling system comprising a plurality of low powered radiotransmitting sets each having a limited broadcast area, and situated atintervals along a transmission line and operatively associatedtherewith. means within. each of said sets whereby the same can berendered operative or inoperative for transmitting purposes, said meansbeing responsive to a modulated carrier outputs of said sets inaccordance with the modulated carrier current to simultaneouslybroadcast from said sets the signals carried by the modulated carrier.

11. A signaling system comprising a transmission line having a carriercurrent superposed thereon, an inductance in series with the line, atransmitting set having a radio frequency waves, and means the radiofrequency waves in accordance with signals carried by the carriercurrent.

12. The method of transmitting signals which consists in impressing acarrier current upon a transmission line carrying direct or lowfrequency currents, modulating said carrier in ac- ALEXANDER N YMAN

